The invention has particular application to snowthrowers and consequently will be described in the following with specific reference to that application, as set out in my prior U.S. Pat. No. 4,852,279. It is to be understood that other applications are intended to be included within the scope of this application.
In known snowthrowers, the blades are helical auger flights. In use, the blade is driven sideways against snow to be removed so that the blade scrapes off or cuts off snow and advances it towards a discharge, either at the end of the blade casing or in the centre, depending upon the blade configuration. At the discharge, an extruder throws the snow through a chute that is adjustable to control the distance and direction of throw. Throwers of any significant size are usually propelled by driven wheels or tracks. Similar characteristics are found in digging implements for earth and sand which employ similar auger arrangements.
A novel blade design for use in conventional snowthrowers was described in my U.S. Pat. No. 4,852,279. This patent describes a blade that is "aggressive" in that it draws itself and the snowthrower forward into the material being removed, so that powered propulsion could be reduced or eliminated in many cases, and replaced by skis or freely rotating wheels.
The present invention is described in relation to the exemplary embodiment set out in U.S. Pat. No. 4,852,279. However, it is to be understood that the improvements described herein may be applicable to other known snowthrowing devices.